Journal ArticleDOI
Picosecond Charge Transfer and Long Carrier Diffusion Lengths in Colloidal Quantum Dot Solids
Andrew H. Proppe,Jixian Xu,Randy P. Sabatini,James Z. Fan,Bin Sun,Sjoerd Hoogland,Shana O. Kelley,Oleksandr Voznyy,Edward H. Sargent +8 more
TLDR
Instead of relying on photoluminescence, this work uses ultrafast transient absorption spectroscopy, a method where sensitivity is undiminished by exciton dissociation, and measures diffusion lengths and interdot charge transfer rates using a 3D donor/acceptor technique.Abstract:
Quantum dots (QDs) are promising candidates for solution-processed thin-film optoelectronic devices. Both the diffusion length and the mobility of photoexcited charge carriers in QD solids are critical determinants of solar cell performance; yet various techniques offer diverse values of these key parameters even in notionally similar films. Here we report diffusion lengths and interdot charge transfer rates using a 3D donor/acceptor technique that directly monitors the rate at which photoexcitations reach small-bandgap dot inclusions having a known spacing within a larger-bandgap QD matrix. Instead of relying on photoluminescence (which can be weak in strongly coupled QD solids), we use ultrafast transient absorption spectroscopy, a method where sensitivity is undiminished by exciton dissociation. We measure record diffusion lengths of ∼300 nm in metal halide exchanged PbS QD solids that have led to power conversion efficiencies of 12%, and determine 8 ps interdot hopping of carriers following photoexcit...read more
Citations
More filters
Journal ArticleDOI
Bipolar-shell resurfacing for blue LEDs based on strongly confined perovskite quantum dots
Yitong Dong,Ya-Kun Wang,Ya-Kun Wang,Fanglong Yuan,Andrew Johnston,Yuan Liu,Dongxin Ma,Min-Jae Choi,Bin Chen,Mahshid Chekini,Se-Woong Baek,Se-Woong Baek,Laxmi Kishore Sagar,James Z. Fan,Yi Hou,Mingjian Wu,Seungjin Lee,Bin Sun,Sjoerd Hoogland,Rafael Quintero-Bermudez,Hinako Ebe,Petar Todorović,Filip Dinic,Peicheng Li,Hao Ting Kung,Makhsud I. Saidaminov,Makhsud I. Saidaminov,Eugenia Kumacheva,Erdmann Spiecker,Liang-Sheng Liao,Oleksandr Voznyy,Zheng-Hong Lu,Edward H. Sargent +32 more
TL;DR: Perovskite QD resurfacing is reported to achieve a bipolar shell consisting of an inner anion shell, and an outer shell comprised of cations and polar solvent molecules, to fabricate blue and green light-emitting diodes with improved mobility.
Journal ArticleDOI
Lattice anchoring stabilizes solution-processed semiconductors
Mengxia Liu,Yuelang Chen,Chih Shan Tan,Rafael Quintero-Bermudez,Andrew H. Proppe,Rahim Munir,Rahim Munir,Hairen Tan,Hairen Tan,Oleksandr Voznyy,Benjamin Scheffel,Grant Walters,Andrew Pak Tao Kam,Bin Sun,Min-Jae Choi,Sjoerd Hoogland,Aram Amassian,Aram Amassian,Shana O. Kelley,F. Pelayo García de Arquer,Edward H. Sargent +20 more
TL;DR: ‘lattice-anchored’ hybrid materials that combine caesium lead halide perovskites with lead chalcogenide CQDs are reported, in which lattice matching between the two materials contributes to a stability exceeding that of the constituents.
Journal ArticleDOI
Cascade surface modification of colloidal quantum dot inks enables efficient bulk homojunction photovoltaics.
Min-Jae Choi,F. Pelayo García de Arquer,Andrew H. Proppe,Ali Seifitokaldani,Jongmin Choi,Junghwan Kim,Se-Woong Baek,Mengxia Liu,Bin Sun,Margherita Biondi,Benjamin Scheffel,Grant Walters,Dae-Hyun Nam,Jea Woong Jo,Olivier Ouellette,Oleksandr Voznyy,Sjoerd Hoogland,Shana O. Kelley,Yeon Sik Jung,Edward H. Sargent +19 more
TL;DR: A cascade surface modification scheme is introduced that provides control over doping and solubility and enables n-type and p-type CQD inks that are fully miscible in the same solvent with complete surface passivation and enables the realization of homogeneous C QD bulk homojunction films that exhibit a 1.5 times increase in carrier diffusion length.
Journal ArticleDOI
Monolayer Perovskite Bridges Enable Strong Quantum Dot Coupling for Efficient Solar Cells
Bin Sun,Andrew Johnston,Chao Xu,Mingyang Wei,Ziru Huang,Zhang Jiang,Hua Zhou,Yajun Gao,Yitong Dong,Olivier Ouellette,Xiaopeng Zheng,Jiakai Liu,Min-Jae Choi,Yuan Gao,Se-Woong Baek,Frédéric Laquai,Osman M. Bakr,Dayan Ban,Oleksandr Voznyy,F. Pelayo García de Arquer,Edward H. Sargent +20 more
TL;DR: In this article, the perovskite layer of colloidal quantum dots (CQDs) is grown after forming the CQD solid, which increases interdot coupling and decreases the distance over which carriers must tunnel.
Journal ArticleDOI
Efficient hybrid colloidal quantum dot/organic solar cells mediated by near-infrared sensitizing small molecules
Se-Woong Baek,Se-Woong Baek,Sunhong Jun,Byeongsu Kim,Andrew H. Proppe,Olivier Ouellette,Oleksandr Voznyy,Changjo Kim,Junho Kim,Grant Walters,Jung Hoon Song,Sohee Jeong,Hye Ryung Byun,Mun Seok Jeong,Sjoerd Hoogland,F. Pelayo García de Arquer,Shana O. Kelley,Jung-Yong Lee,Edward H. Sargent +18 more
TL;DR: Baek et al. as discussed by the authors introduced small molecules that act as a bridge between colloidal quantum dots and polymers, thus improving device efficiency and stability, and the resulting hybrid solar cells exhibit PCEs of 13.1% and retain over 80% of their initial PCE after 150h of continuous operation unencapsulated, outperforming present air-processed solution-cast CQD/organic photovoltaics.
References
More filters
Journal ArticleDOI
Quantum Dot Solar Cells. Semiconductor Nanocrystals as Light Harvesters
TL;DR: In this paper, three major ways to utilize semiconductor dots in solar cell include (i) metal−semiconductor or Schottky junction photovoltaic cell, (ii) polymer−smiconductor hybrid solar cell, and (iii) quantum dot sensitized solar cell.
Journal ArticleDOI
Emergence of colloidal quantum-dot light-emitting technologies
TL;DR: In this paper, the authors summarized the key advantages of using quantum dots as luminophores in light-emitting devices (LEDs) and outlined the operating mechanisms of four types of QD-LEDs.
Journal ArticleDOI
Impurity Conduction at Low Concentrations
A. J. Miller,Elihu Abrahams +1 more
TL;DR: In this paper, the conductivity of an n-type semiconductor has been calculated in the region of low-temperature $T$ and low impurity concentration ${n}_{D}$.
Journal ArticleDOI
Solution-processed PbS quantum dot infrared photodetectors and photovoltaics
Steve Mcdonald,Gerasimos Konstantatos,Shiguo Zhang,Paul W. Cyr,Ethan J. D. Klem,Larissa Levina,Edward H. Sargent +6 more
TL;DR: Sittingizing conjugated polymers with infrared-active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers, and makes use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.
Journal ArticleDOI
Ultrasensitive solution-cast quantum dot photodetectors
Gerasimos Konstantatos,Ian A. Howard,Armin Fischer,Sjoerd Hoogland,Jason Paul Clifford,Ethan J. D. Klem,Larissa Levina,Edward H. Sargent +7 more
TL;DR: The tailored selection of absorption onset energy through the quantum size effect, combined with deliberate engineering of the sequence of nanoparticle fusing and surface trap functionalization, underlie the superior performance achieved in this readily fabricated family of devices.